Re- and allotransplantation of teeth--an experimental study in monkeys

In each of six monkeys one of the permanent lateral incisors with uncompleted root development was replanted. At the same time the contralateral incisors in four of the monkeys were allotransplanted by pairs. The remaining two contralateral incisors served as controls. After 4 weeks and 4 months, respectively, three monkeys were decapitated and the upper lateral incisors with adjacent periodontal tissue were examined histologically. The replanted teeth in five cases had a vital pulp. In the sixth case, however, the replanted incisor exhibited pulpitis and partial necrosis of the pulp. The periodontal membrane had a normal histologic appearance. In two cases a small area of arrested root resorption was observed. With the allotransplanted teeth the histologic appearance was altered. After 4 weeks a pronounced inflammatory reaction was observed in both the pulpal tissue and the periodontal membrane. The pulp was in most cases necrotic, and marked root resorption was observed. Most of the allotransplanted teeth were resorbed and replaced by an irregular hard tissue that resembled osteoid, which in many cases was connected with the tooth remnants by ankylosis. These results indicate that allotransplanted teeth, in contrast to replanted teeth, exhibit the characteristic features of an allograft rejection, including an inflammatory reaction and resorption.